Fluidic sound amplification system

Abstract

A fluidic sound amplification system couples successive laminar proportional amplifiers through acoustic radiation between output and input horns to avoid the propagation of null offset signals. A second approach to obviating DC null bias in a fluidic sound amplification system comprises splitting the input signal, effecting a selected time delay on a portion of the signal such that the bandpass frequencies and dead zones or cancellation frequencies respectively of the amplified signals are 180° out of phase and combine to produce a near uniform frequency response. A third approach is to use multiple parallel elements in each stage of amplification in such a manner that mechanical errors cancel each other out.

What is claimed is: 
     
       1. A method of acoustically coupling first and second laminar proportional fluidic amplifiers (LPAs) comprising the steps of: radiating an acoustic output signal from a first of said stages through an unconfined air space; and   receiving the radiated acoustic output signal at the other of said LPAs from said space without direct connection and without direct coupling to said first LPA.   
     
     
       2. A method for fluidically amplifying sound comprising the steps of: (a) splitting an input sound signal into first and second split signals;   (b) imposing a selected time delay on said first split signal;   (c) transmitting said time-delayed first split signal;   (d) transmitting said second signal undelayed;   (e) receiving said timed delay first signal at a laminar proportional fluidic amplifier (LPA), and splitting the received first signal into third and fourth signals;   (f) imposing a selected time delayed on said third split signal;   (g) transmitting said time delayed third signal;   (h) transmitting said fourth signal;   (i) receiving at a further LPA said second signal;   (j) splitting said second signal into fifth and sixth signals;   (k) imposing a selected time delay on said fifth signal;   (l) transmitting said fifth signal;   (m) transmitting said sixth signal;   (n) combining said fourth and fifth signals into a seventh signal; and   (o) combining said third and sixth signals into an eighth signal; wherein said seventh and eighth signals correspond to output signals.   
     
     
       3. A fluidic sound amplification system comprising at least first and second laminar proportional fluidic amplifiers (LPAs) staged in sequence from an upstream unamplified input side to a downstream amplified output side; and acoustic coupling between said first and second LPAs including means for radiating output soundwaves from said first LPA through an unconfined open space and means for receiving said radiated soundwaves from said space as input soundwaves at said second LPA, wherein said acoustic coupling is devoid of any enclosed signal conduit for conducting said output soundwaves between said first and second LPAs. 
     
     
       4. The fluidic sound amplification system of claim 1 wherein at least one of said laminar proportional fluidic amplifiers is a differential amplifier. 
     
     
       5. The fluidic sound amplification system of claim 1 wherein at least one of said laminar proportional fluidic amplifiers is a single input-single output fluidic amplifier. 
     
     
       6. The fluidic sound amplification system of claim 1 wherein at least one of said laminar proportional fluidic amplifiers comprises multiple parallel differential amplifier channels. 
     
     
       7. The fluidic sound amplifier system of claim 1 wherein said means for radiating said output soundwaves includes at least one output horn. 
     
     
       8. The fluidic sound amplifier system of claim 7 wherein said at least one output horn is conical in shape. 
     
     
       9. The fluidic sound amplifier system of claim 7 wherein said at least one output horn is exponential in shape. 
     
     
       10. The fluidic sound amplifier system of claim 7 wherein said at least one input horn is exponential in shape. 
     
     
       11. The fluidic sound amplifier system of claim 1 wherein said means for receiving said input soundwaves includes at least one input horn. 
     
     
       12. The fluidic sound amplifier system of claim 11 wherein said at least one input horn is conical in shape. 
     
     
       13. The fluidic sound amplification system of claim 1 wherein the distance between said LPAs across said space is sufficient to dissipate DC flow. 
     
     
       14. A fluidic sound amplification system comprising: a plurality of two channel differential laminar proportional fluidic amplifiers (LPAs) staged and acoustically coupled in adjacent sequence from an upstream unamplified input side to a downstream amplified output side;   at least a first of said LPAs having output two horns connected respectively to its two said channels for acoustically radiating signals, and at least a second of said LPAs adjacent and downstream of said first LPA having two input horns connected to its said two channels, respectively, for receiving respective signals radiated from said two output horns; and   wherein said output horns ale separated from said input horns across an unconfined open space by a sufficient distance to dissipate DC flow from said output horns to said input horns.   
     
     
       15. The fluidic sound amplification system of claim 14 further comprising an acoustic separator disposed in said space for preventing cross-coupling between said acoustically radiated signals from said two output horns. 
     
     
       16. The fluidic sound amplification system of claim 15 wherein alternate pairs of adjacent LPAs in said sequence are acoustically coupled across respective unconfined open spaces by input and output horns, and wherein other alternate pairs of adjacent LPAs in said sequence are direct coupled by enclosed flow passages. 
     
     
       17. The fluidic sound amplification system of claim 1, wherein originating sound generated at one location is amplified by said system for broadcast over a prescribed area, said system further comprising: additional cascaded stages of LPAs, a last LPA stage of which delivers a final amplified acoustic signal; and   at least one last stage horn connected to said last LPA stage to radiate said amplified acoustic output signal throughout at least a portion of said prescribed area.   
     
     
       18. The fluidic sound amplification system of claim 17 further comprising near field cancellation means for broadcasting from said system, at a location proximate said one location, an acoustic signal 180° out-of-phase with said amplified acoustic output signal to cancel said amplified acoustic output signal and permit only the originating sound to be heard proximate said one location. 
     
     
       19. The fluidic sound amplification system of claim 17 wherein said additional cascaded stages include multiple parallel-connected last LPA stages each located in a respective section of said prescribed area, each last LPA stage delivering a respective final amplified acoustic output signal; and multiple last stage horns, each connected to a respective last LPA stage to radiate said amplified acoustic output signal from said respective last LPA stage throughout a respective section of said prescribed area.   
     
     
       20. A fluidic sound amplifier comprising a first differential laminar proportional amplifier (LPA) having means for splitting an input signal into a first and a second signal, means for imposing a selected time delay on said first split signal, a first output port for transmitting said time-delayed first signal and a second output port for transmitting said undelayed second signal; a second differential LPA staged to receive said time delayed first signal and having means for splitting said time delayed first signal into a third and fourth signal, means for imposing a selected time delay on said split third signal, a third output port for transmitting said time-delayed third signal and a fourth port for transmitting said fourth signal;   a third differential LPA staged to receive said second signal and having means for splitting said second signal into a fifth and sixth signal, means for imposing a selected time delay on said split fifth signal, a fifth output port for transmitting said fifth signal and a sixth port for transmitting said sixth signal; and   means for combining said fourth and fifth signals into a single seventh output signal and means for combining said third and sixth signals into a single eighth output signal.   
     
     
       21. A fluidic sound amplifier for receiving an input signal and producing an amplified signal free of DC null biases in a frequency band centered at a selected frequency comprising: means for splitting said input signal into a first and a second input signal;   means for conducting said first signal to the left input port of a first differential laminar proportional amplifier and said second signal to the right input port of said first amplifier;   means for effecting a 180° phase delay at a selected frequency in said second signal arriving at said first amplifier right input port relative to said first signal arriving at said first amplifier left input port;   means for splitting the left output signal of said first amplifier into a third and a fourth input signal;   means for splitting the right output signal of said first amplifier into a fifth and a sixth input signal;   means for conducting said third signal to the left input port of a second differential laminar proportional amplifier and said fourth signal to the right input port of said second amplifier;   means for conducting said fifth signal to the left input port of a third differential laminar proportional amplifier and said sixth signal to the right input port of said third amplifier;   means for effecting a 180° phase delay at said selected frequency in said third signal arriving at said second amplifier left input port relative to said fourth signal arriving at said second amplifier right input port;   means for effecting a 180° phase delay at said selected frequency in said sixth signal arriving at said third amplifier right input port relative to said fifth signal arriving at said third amplifier left input port;   means for combining said second amplifier left output signal with said third amplifier left output signal; and   means for combining said second amplifier right output signal with said third amplifier right output signal.   
     
     
       22. The fluidic sound amplifier system of claim 21 wherein said 180° phase delays are effected by selectively varying the difference in path lengths through which signals are conducted to left and right input ports. 
     
     
       23. The fluidic sound amplification system of claim 22 wherein said difference in path lengths for said 180° phase delay is determined according to the equation ΔL 180  =(2n-1)c/2f where ΔL 180  is said path length difference, c is the speed of sound, n is the harmonic number and f is said selected frequency. 
     
     
       24. A fluidic sound amplification system having a first and a second fluidic sound amplifier according to claim 16 for receiving an input signal and producing an amplified signal having a near uniform frequency response free of DC null biases across a frequency band centered at a selected frequency comprising: means for splitting said input signal into a first and a second input signal;   said first fluidic sound amplifier having a 180° phase delay at said selected frequency;   said second fluidic sound amplifier having a 360° phase delay at said selected frequency;   means for conducting said first input signal to said first amplifier and said second input signal to said second amplifier; and   means for combining the output signals of said first and said second sound amplifiers.   
     
     
       25. The fluidic sound amplification system of claim 24 wherein said phase delays are effected by selectively varying the difference in path lengths through which signals are conducted to left and right input port. 
     
     
       26. The fluidic sound amplification system of claim 25 wherein said difference in path lengths for said 180° phase delay is determined according to the equation   ΔL.sub.180 =(2n-1)c/2f     where ΔL 180  is the path length difference, c is the speed of sound, n is the harmonic number and f is said selected frequency.   
     
     
       27. The fluidic sound amplification system of claim 25 wherein said difference in path lengths for said 360° phase delay is determined according to the equation   ΔL.sub.360 =(2n)c/2f     where ΔL 360  is the path length difference, c is the speed of sound, n is the harmonic number and f is said selected frequency.   
     
     
       28. A fluidic sound amplification system comprising: first and second laminar proportional fluidic amplifiers (LPAs) each comprising at least a first input port for receiving an acoustic input signal and at least a first output port for providing a first acoustic output signal representing an amplified version of said acoustic input signal;   means acoustically coupling said first and second LPAs by positioning the first output port of said first LPA in physically spaced relation to said first input port of said second LPA across an open unconfined air space such that said first acoustic output signal from said first LPA is radiated through said unconfined air space and received as an acoustic input signal by the first input port of said second LPA.   
     
     
       29. The system of claim 28 further comprising: a first outlet horn connected to said first output port of said first LPA for radiating said first acoustic output signal into said unconfined air space; and   a first inlet horn connected to the first input port of said second LPA for receiving the first acoustic output signal from said first LPA across said unconfined air space.   
     
     
       30. The system of claim 29 wherein said first LPA includes a second output port and a second outlet horn connected to said second output port, the first and second output ports of said first LPA being arranged to provide a differential pressure output signal thereacross proportional to the acoustic input signal received at the input port of said first LPA; wherein said second LPA includes a second input port and a second inlet horn connected to said second input port, said first and second input ports of said second LPA being arranged to provide a differential pressure input signal to said second LPA;   wherein said second inlet horn is positioned in spaced relation to the second outlet horn across said unconfined air space such that acoustic signals radiated through said unconfined air space from said second outlet horn are received as acoustic input signals by said second inlet port.   
     
     
       31. The system of claim 30 further comprising an acoustic separator disposed in said unconfined air space for preventing cross-coupling between said acoustic signals radiated from said first and second outlet horns of said first LPA.